The present disclosure relates to an image reading device that reads a placed document.
Some image reading devices include a contact glass (platen glass). A document is placed on the contact glass. The image reading device reads the document on the contact glass. One example as described above is known of technology for reading a document on a contact glass.
Specifically, in a known image forming apparatus, the width in the main scanning direction of a document placed on a document stage is sensed by an image sensor for reading images, and there are provided a means for emitting light toward an image sensor that is movable in the sub scanning direction of the document, a stopper for restricting the movement range of the light-emitting means, and a means for operation for specifying the stop position of the stopper. This structure is intended to accurately scan only a region corresponding to the size of a document with simple operation when a document of an irregular size is read.
A user places a document on the document stage. When the document placed on the document stage is read, a light source radiates light toward the document stage. A carriage includes the light source. The carriage moves in the sub scanning direction. As the carriage is moved in the sub scanning direction, the position of the reading line moves in the sub scanning direction. Through repeated reading (scanning) while the reading line is moving, the whole document placed on the document stage is read. A document smaller than a set reading range can be placed.